Subwoofer Driver

[randallp]

Good afternoon!

I have a couple of questions. I am a proud owner of a pair of Martin Logan Ascent i speakers and would like to add a 12" sub (2 preferred as my home theater is over my 3 car garage). I'm on a budget so i am trying to keep it around $800. . Here are my questions::

1. Are there any budget powered subs on the market today you could recommend based on budget such as the BIC PL-200 or other that are quick and perform well with movies and music?

2. I'm a DIY kind of person and thinking i may be able to get more bang for my buck by spending the majority of my budget on 2 12" drivers. What drivers would you recommend as i will build the boxes for them. They Do not have to be powered.

Thank you and I look forward to hearing from you!

 

[Kruppy]

Check out www.rythmikaudio.com

Rythmik is an ID (internet direct) company that makes high performance at a moderate cost servo subwoofers. They also cater to the DIY’ers with driver/amp kits and if I’m not mistaken, provide box plans. There is a Rythmik specific thread in the subwoofers section of AVSforum. The owner, Brian Ding, is fairly accessible and responds often in that thread.

Their 12” F12 sub (complete) starts at $874 while the 15” F15 starts at $974. There are both sealed and ported versions of both subs. In addition, there are various 12” driver choices.

I own a F15HP 15” Rythmik sub and have been very happy with it.

 

[JonFo]

Randal, since you are: A) over a big space (three car garage) and B) willing to DIY and C) limited budget, then that spells Infinite Baffle sub to me.

For less than $800 you will get a subwoofer that performs better than many >$3K closed box subs.

Do spend some time on the Cult of the Infinitely baffled and get some help there.

Step one is to pick the ideal location for a sub, so do borrow a friends sub and get some kind of measurement rig that is accurate in the low frequencies and plot out the ideal spot. Good starting places IMHO are: mid-way across the front of the room between the front speakers.

Please read up on my IB experience at my site (and follow the links from there to the Cult of IB).

It matches the ML's perfectly, with extremely low-distortion and very high output capabilities.
Total cost for mine was around $1,300 for parts (including an amp). If just doing a 2x 15", your cost for drivers could be under $500.

 

[randallp]

Kruppy and JonFo thanks for the response and both give me a good place to start/consider and within budget .

I'm leaning toward building two cabinets myself with a single 12" front facing driver in each. What 12" drivers would you recommend that are clean, perform well in both the theater and musical environment, perform at the low end of the spectrum, and will match well with my Ascent i's?

Finally, should I build a sealed or ported box based on your experience and what i'm trying to accomplish?

Thank you so much!

 

[Kruppy]

I'm leaning toward building two cabinets myself with a single 12" front facing driver in each. What 12" drivers would you recommend that are clean, perform well in both the theater and musical environment, perform at the low end of the spectrum, and will match well with my Ascent i's.

Finally, should I build a sealed or ported box based on your experience and what i'm trying to accomplish?

Driver types...this is where I must defer to those with more experience than myself. If going the Rythmik direction I would suggest spending some time going over the information on their website (there is quite a bit), reviewing the AVSforum thread, and even emailing Brian through the website. He's a pretty busy guy, but should get back to you with suggestions/direction in a day or two. http://www.avsforum.com/t/1214550/official-rythmik-audio-subwoofer-thread

Ported vs sealed, this is a very personal preference decision. I think the general consensus is that sealed subs are more musically oriented while ported subs are thought to be more for home theater. The ported Rythmik servo subs are being sold/marketed as rivaling sealed sub sound with being able to handle home theater output. Personal choice and depends on what your preference is. Again best to do some research and audition if possible (I know, difficult with an internet company).

My sub is 15" sealed sub with Ascents and I think the play well together, however, with my room acoustic issues I wish I had a second sub.

 

[Tosh]

Randallp, before adding subs, you might consider using an active xo on only the bass of your Ascents. This would mean bypassing the passive xo (inductor and capacitor) for the woofer inside the cabinet (some soldering), but the results are well worth the extra amplifier and active xo, plus you get to hear how deep, articulate, and quick the bass really can be, even from a 10 inch woofer.... (And it helps take a load off the amp for the ESL portion.)

 

[randallp]

Randallp, before adding subs, you might consider using an active xo on only the bass of your Ascents. This would mean bypassing the passive xo (inductor and capacitor) for the woofer inside the cabinet (some soldering), but the results are well worth the extra amplifier and active xo, plus you get to hear how deep, articulate, and quick the bass really can be, even from a 10 inch woofer.... (And it helps take a load off the amp for the ESL portion.)

Hey Tosh,

I have a separate amp on the 10" ML subs and need more low end based on my room size. The 10's are exceptionally well matched and fast. I don't want to muddy the sound up by adding slower subs. Any thoughts on drivers that match well with the Ascent i's?

Or if there is a powered sub you recommend under $800?

Thank you all for you advice!

 

[Tosh]

It sounds like you are passively bi-amping? Actively crossing over eliminates the inductor, a coil which causes the amp to lose control of the woofer and make things boomy. If you think you have fast bass with a passive xo (inductor coil) before the woofer, then you will be SHOCKED once you go active....(I'm sorry I put it off so long myself.)

It's still possible you may need a proper sub for LF effects in a large room, but going active on the Ascent's bass is something you owe yourself to try before adding a sub.

 

[randallp]

It sounds like you are passively bi-amping? Actively crossing over eliminates the inductor, a coil which causes the amp to lose control of the woofer and make things boomy. If you think you have fast bass with a passive xo (inductor coil) before the woofer, then you will be SHOCKED once you go active....(I'm sorry I put it off so long myself.)

It's still possible you may need a proper sub for LF effects in a large room, but going active on the Ascent's bass is something you owe yourself to try before adding a sub.

Would you mind walking me through how to do this or directing me to a website that contains this info? Sorry! Just don't want to mess anything up.

Currently I have one amp driving the the panels and a second driving the subs.

Thanks!

 

[Tosh]

The 'trick' is first finding an active low-pass xo that can be set for your xo frequency (280Hz for Ascent, 250Hz for SL3, 12dB/oct). Then, inside the cabinet, you will need to bypass the inductor (essentially shorting it by soldering a piece of wire across it, or actually de-soldering it) and then disconnecting (desoldering) the electrolytic cap (which is in parallel with the woofer) at one of its terminals. This eliminates the passive xo (inductor and cap), leaving the woofer directly connected to the woofer's binding posts.

I had an old Pyramid PR3000 active xo in which I changed some resistors to set it for 250Hz, but I don't see these available these days...

 

[randallp]

The 'trick' is first finding an active low-pass xo that can be set for your xo frequency (280Hz for Ascent, 250Hz for SL3, 12dB/oct). Then, inside the cabinet, you will need to bypass the inductor (essentially shorting it by soldering a piece of wire across it, or actually de-soldering it) and then disconnecting (desoldering) the electrolytic cap (which is in parallel with the woofer) at one of its terminals. This eliminates the passive xo (inductor and cap), leaving the woofer directly connected to the woofer's binding posts.

I had an old Pyramid PR3000 active xo in which I changed some resistors to set it for 250Hz, but I don't see these available these days...

So essentially the woofer bypasses any crossover technology in the cabinet connecting direct to the amp that's connected to a crossover?

 

[Tosh]

Correct. And this 'active' or 'electronic' crossover is set to the correct xo frequency, slope, and level (to match level of ESL amp -- and useful to adjust bass/ESL level for certain recordings) and then into the woofer amp, which is connected to the woofer terminals.

If I were to start from scratch, I would use a digital crossover for ESL XO and EQ, and the bass (like JonFo does), but a cheapie analog op-amp based electronic crossover like my Pyramid is good enough to pass bass -- I would not pass the ESL portion through these op-amps....